We examined the ability of four American screening tests to identify preschool-age Canadian children with language delays. At 54 months, 110 children from five Ontario infant and child development programs completed the Ages and Stages Questionnaire, Battelle Developmental Inventory Screening Test, Brigance Preschool Screen, and Early Screening Profiles. Their results on the language measures were then compared with their performance on the Preschool Language Scales, 4th ed., and the Bracken Basic Concepts Scale—Revised at 5 years. None of the screening tests had adequate sensitivity (SN) and specificity (SP) when identifying receptive language delays; only one screen had adequate SN and SP for expressive language delays. Adjusting cutoffs based on ROC curve analyses improved the ability of some screens to identify language delays, but combining tests did not improve discriminability. Our results indicate that language screening measures are not interchangeable. We recommend the provision of detailed SN and SP information for each scale of screening tests so that early interventionists can evaluate the adequacy of each component of a screening test. When norming tests, appropriate analyses should be conducted to determine whether American norms are appropriate for use with Canadian children, given the differences in the demographics and educational systems of the two countries.